Fig. 4From: Analytic time-of-flight positron emission tomography reconstruction: two-dimensional caseA typical plot for the noise-control Fourier-domain window function W(ω) with k = 1000 and α = 0.0001. The horizontal axis is the frequency ω: 0 ≤ ω ≤ 0.5. The vertical axis is the gain W(ω), which suggests a low-pass filterBack to article page